Re: [PATCH] wifi: ath12k: fix channel list double-free on error paths

[Rameshkumar Sundaram <rameshkumar.sundaram@oss.qualcomm.com>]

On 7/31/2026 3:08 PM, Linkai Gong wrote:
> ath12k_mac_setup_channels_rates() frees band channel arrays on failure
> but either leaves the pointers non-NULL or clears the wrong band. Later
> ath12k_mac_cleanup_unregister() frees the same pointers again.
> 
> Clear the correct sbands[].channels pointers after kfree(), including
> a copy-paste bug that nulled 2 GHz after freeing 6 GHz channels.
> 
> Fixes: acc152f9be20 ("wifi: ath12k: combine channel list for split-phy devices in single-wiphy")
> Signed-off-by: Linkai Gong <gonglinkai@kylinos.cn>
> ---
>   drivers/net/wireless/ath/ath12k/mac.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/ath/ath12k/mac.c b/drivers/net/wireless/ath/ath12k/mac.c
> index a0928890671a..5468a8d2d5d5 100644
> --- a/drivers/net/wireless/ath/ath12k/mac.c
> +++ b/drivers/net/wireless/ath/ath12k/mac.c
> @@ -14275,6 +14275,7 @@ static int ath12k_mac_setup_channels_rates(struct ath12k *ar,
>   					   sizeof(ath12k_6ghz_channels), GFP_KERNEL);
>   			if (!channels) {
>   				kfree(ar->mac.sbands[NL80211_BAND_2GHZ].channels);
> +				ar->mac.sbands[NL80211_BAND_2GHZ].channels = NULL;
>   				return -ENOMEM;
>   			}
>   
> @@ -14325,7 +14326,9 @@ static int ath12k_mac_setup_channels_rates(struct ath12k *ar,
>   					   GFP_KERNEL);
>   			if (!channels) {
>   				kfree(ar->mac.sbands[NL80211_BAND_2GHZ].channels);
> +				ar->mac.sbands[NL80211_BAND_2GHZ].channels = NULL;
>   				kfree(ar->mac.sbands[NL80211_BAND_6GHZ].channels);
> +				ar->mac.sbands[NL80211_BAND_6GHZ].channels = NULL;
>   				return -ENOMEM;
>   			}
> 


Above two hunks seem to fix older allocation-failure paths which
already existed before acc152f9be20. In current history those lines 
blame back to d889913205cf ("wifi: ath12k: driver for Qualcomm IEEE 
802.11ax devices").

So this probably should either be split into two fixes, or the commit
message/Fixes tag should be adjusted.

But unless there is another reachable path where these stale pointers 
are later freed or dereferenced, do we really need a Fixes tag here?




> @@ -14365,7 +14368,7 @@ static int ath12k_mac_setup_channels_rates(struct ath12k *ar,
>   					kfree(ar->mac.sbands[NL80211_BAND_2GHZ].channels);
>   					ar->mac.sbands[NL80211_BAND_2GHZ].channels = NULL;
>   					kfree(ar->mac.sbands[NL80211_BAND_6GHZ].channels);
> -					ar->mac.sbands[NL80211_BAND_2GHZ].channels = NULL;
> +					ar->mac.sbands[NL80211_BAND_6GHZ].channels = NULL;
>   					kfree(channels);
>   					band->channels = NULL;
>   					return ret;



--
Ramesh